JP3398971B2 - Electric double layer capacitor and method of manufacturing the same - Google Patents

Abstract

PURPOSE:To reduce volume resistivity of polalizable electrodes, and decrease the inner resistance of an electric double layer capacitor using the polarizable electrodes, by using polarizable electrodes composed of sintered bodies of polymer of thermosetting binder which melts at a temperature lower than or equal to the curing temperature and monomer having reactivity with the thermosetting binder. CONSTITUTION:Phenol resin powder (Ph) as thermosetting binder which melts at a temperature lower than or equal to the curing temperature, and methyl methacrylate (MMA) as monomar having reactivity with the thermosetting binder are polymerized in methanol solution by applying ammonium cerium (IV) nitrate to initiator, thus forming Ph-MMA polymer. The Ph-MMA polymer is mixed with powder activated carbon whose raw material is phenol resin, press-molded, and then sintered in an inactive atmosphere, thereby forming polarizable electrodes 8. The polarizable electrodes 8 are impregnated with electrolyte, and an electric double layer capacitor is constituted by using a separator 9 and collectors 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric double layer capacitor having a reduced internal resistance and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, an electric double layer capacitor whose internal resistance is reduced has, for example, the structure shown in FIG. In FIG. 3, 1 is a polarizable electrode obtained by sintering a press-molded body of activated carbon powder and a thermosetting binder, 2 is a current collector, 3 is a separator, and 4 is a gasket.

Further, the polarizable electrode 1 will be described in detail with reference to FIG. 4, in which 5 is an activated carbon powder, 6 is a thermosetting binder after press sintering, and 7 is a thermosetting binder during press sintering. It is a void caused by volume contraction.

[0004]

However, in the above-mentioned conventional structure, a press-molded body of a thermosetting binder and activated carbon is used by sintering as a polarizable electrode. The press molded body is formed by the following bonding.

(1) Chemical bond between thermosetting binder and thermosetting binder (2) Non-chemical bond between thermosetting binder and activated carbon Therefore, during sintering, the thermosetting binder decomposes,
Since it is carbonized and the volume is contracted, a void is generated in the polarizable electrode. As a result, there is a problem that the polarizable electrode has a high volume resistivity, and thus the electric double layer capacitor using the polarizable electrode has a high internal resistance.

An object of the present invention is to solve the above-mentioned conventional problems and to provide an electric double layer capacitor in which the polarizable electrode has a low volume specific resistance and a low internal resistance.

[0007]

In order to achieve the above object, the polarizable electrode contains a thermosetting binder containing activated carbon and a binder as main components, and has a reactivity with the thermosetting binder. A polymer obtained by sintering a polymer with a monomer is used, and as the thermosetting binder, one that melts at a temperature below the curing temperature is used.

[0008]

With the above structure, the polarizable electrode is obtained by sintering a polymer of a thermosetting binder and a monomer having reactivity, and the polymer is formed by the following bond. Chemical bond between curable binder and thermosetting binder (2) Non-chemical bond between thermosetting binder and activated carbon (3) Between thermosetting binder and monomer reactive with the thermosetting binder (4) Polymer of the thermosetting binder and the monomer reactive with the thermosetting binder during non-chemical bonding sintering of the monomer reactive with the thermosetting binder and activated carbon Is decomposed and carbonized and the volume is contracted, so that a void is generated inside the polarizable electrode.

However, since there is a chemical bond between the thermosetting binder and the monomer having reactivity with the thermosetting binder in the polymer, the volume shrinkage is reduced as compared with the conventional example, and the above-mentioned amount is reduced. The conductive path between the activated carbons becomes thick in the polar electrode. As a result, the volume specific resistance of the polarizable electrode is lowered, which in turn contributes to the reduction of the internal resistance of the electric double layer capacitor using the polarizable electrode.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 8 is a polarizable electrode containing activated carbon and a binder as main components, 9 is a separator, and 10 is a current collector.

Further, the polarizable electrode 8 is enlarged and shown in detail in FIG.
11, 11 is activated carbon, 12 is a polymer of a thermosetting binder after sintering and a monomer having reactivity with the thermosetting binder, and 13 is generated by volume shrinkage of the polymer during press sintering. It is a void.

A manufacturing method for manufacturing an electric double layer capacitor will be specifically described below. 10 g of a phenol resin powder (hereinafter abbreviated as Ph) which is a thermosetting binder that melts at a curing temperature or lower, and methyl methacrylate (hereinafter, MMA) which is a monomer reactive with the thermosetting binder.
Abbreviated. 1 g) is polymerized in a methanol solution with dicerium ammonium nitrate as an initiator to form a Ph-MMA polymer. 11 g of the Ph-MMA polymer and powdered activated carbon (specific surface area 1500 m ²
/ G) 50 g are mixed, and after press molding at a pressing pressure of 300 kg / cm ² and a pressing temperature of 150 ° C., 100 in an inert atmosphere
It was sintered at 0 ° C. to form a polarizable electrode.

30% by weight of the polarizable electrode as an electrolytic solution
Was impregnated with sulfuric acid, a polyethylene porous film was used as a separator, and a platinum foil was used as a current collector to form an electric double layer capacitor.

Although the phenol resin powder is used as the thermosetting binder, it is not limited to this as long as it is a thermosetting binder that melts at the curing temperature or lower.

Although MMA was used as the monomer,
The monomer is not limited to this as long as it is a monomer having reactivity with the thermosetting binder.

Although a thermosetting binder that melts at a temperature below the curing temperature and a monomer reactive with the thermosetting binder were polymerized in methanol using an initiator, the polymerization method is not limited to this. Absent.

Although phenolic resin powder activated carbon was used as the activated carbon, the raw material and shape are not limited to this.

Although 30% by weight of sulfuric acid was used as the electrolytic solution, the electrolytic solution is not limited to this.

Although a polyethylene porous film is used as the separator, it is non-electroconductive and ion-permeable,
Any material that does not react with the electrolytic solution may be used.

Although platinum foil is used as the collector, it is not limited to this as long as it is electron conductive and does not react with the electrolytic solution.

The volume resistivity of the polarizable electrode of the electric double layer capacitor according to the present invention and the internal resistance of the electric double layer capacitor are shown in Table 1 in comparison with the conventional example.

10 g of a phenol resin powder (hereinafter abbreviated as Ph) which is a thermosetting binder that melts at a curing temperature or lower is mixed with 40 g of powdered activated carbon (specific surface area 1500 m ² / g) made of a phenol resin. After press molding at a pressing pressure of 300 kg / cm ² and a pressing temperature of 150 ° C,
A polarizable electrode formed by sintering in an inert atmosphere at 1000 ° C. was impregnated with 30% by weight of sulfuric acid as an electrolytic solution, a polyethylene porous film was used as a separator, and a platinum foil was used as a current collector. An electric double layer capacitor is used as a conventional example.

[0024]

[Table 1]

[0025]

As is apparent from the above description, the electric double layer capacitor of the present invention comprises a polymer of a thermosetting binder that melts at a curing temperature or lower and a monomer that is reactive with the thermosetting binder. Since the binder made of a sintered body and the polarizable electrode made of activated carbon are used, the volume specificity of the polarizable electrode can be reduced, and thus the internal resistance of the electric double layer capacitor can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an electric double layer capacitor according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a polarizable electrode of an electric double layer capacitor according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional electric double layer capacitor.

FIG. 4 is an enlarged view of a polarizable electrode of a conventional electric double layer capacitor.

[Explanation of symbols]

8 Polarizable electrode obtained by sintering a press-molded body of activated carbon powder and thermosetting binder 9 Separator 10 Gasket 11 Activated carbon powder 12 Thermosetting binder after press sintering 13 Volume of thermosetting binder after press sintering Void created by contraction

(72) Inventor Seiji Nonaka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP 63-151010 (JP, A) JP 64-50405 (JP) , A) JP 60-27113 (JP, A) JP 64-1219 (JP, A) JP 4-288361 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) H01G 9/058

Claims (2)

(57) [Claims] 1. A polarizable electrode, a separator, an electrolytic solution,
The polarizable electrode is provided with a current collector, contains a thermosetting binder containing activated carbon and a binder as main components, and is obtained by sintering a polymer of the thermosetting binder and a monomer having reactivity. The thermosetting binder melts at a temperature not higher than its curing temperature. 2. A step of forming a polymer of a thermosetting binder that melts at a curing temperature or lower and a monomer having reactivity with the thermosetting binder; a step of mixing the polymer and activated carbon; To form a polarizable electrode by sintering the polymer and activated carbon thus prepared, a step of impregnating the polarizable electrode with an electrolytic solution, and an electric double layer capacitor using the polarizable electrode impregnated with the electrolytic solution. A method of manufacturing an electric double layer capacitor having a step of assembling.